A variety of different types of hot-wire anemometers have been produced and sold, including ones that use a thin wire suspended between two prongs (hereafter referred to as a “wire-type”) and ones that have a thin film deposited on a substrate (hereafter referred to as a “film-type”).
In the case of wire-type anemometers, the device is typically configured as an elongated probe or wand and includes a thin wire that acts as the sensing element and is stretched between two prongs mounted to the end of a probe body. The prongs hold the tightly stretched wire therebetween so that the wire can be exposed to the fluid being measured, which is typically a gas or a non-conducting liquid. The small wire diameter can make the devices expensive to manufacture and fragile to handle.
Film-type anemometers, on the other hand, typically use a thin metal film directly deposited on an electrically insulated substrate. The thin metal film acts as the sensing element and is usually monolithically formed on the substrate using micro-fabrication techniques. While film-type anemometers can be more robust and durable than some wire-type anemometers, they may not perform well in some environments such as in certain open and unenclosed spaces, or they may require a large amount of area on the substrate.